Drop penetration test

Figure 13.5 Droplets of aqueous dyestuff solution as employed for the TEGEWA drop penetration test on a hydrophobized PET fabric. The photographs clearly show a significant difference in the contact angles of the two droplets, which might be due to the clearly visible fabric distortion as well as local variations in microscopic features of the fabric geometry, i.e. pore sizes and capillary system.

The drop penetration test was developed by Sookne et al. [168]. The apparatus consists of a drop-forming device with capillaries mounted at the bottom of a container, a tube to shield the spray from draft, and a sample holder designed to collect the water penetrating the fabric. The time needed to collect 10 mL of water is measured. 

Soil Column Tests. In the sand penetration test, a minimal amount of water was used. No consideration was given to the hydrostatic pressure which would occur in nature from a body of surface water. A new soil infiltration test was developed to take this into consideration. This test used a maximum amount of water (200 mL) on a minimum amount of treated soil (10 g) and was restricted only by the dimensions of the laboratory equipment. Our aim was to prepare an hydrophobe for soil which would support water over an extended period of time. Whereas water passed through soil treated with hydrophilic compounds within 8 hr, 2 weeks or more were required for penetration through an hydrophobe-treated soil. In the latter case the water level dropped 6 mm or less each day, showing that the cationic surfactant greatly hindered, but did not completely restrict the passage of water. The tests were usually terminated after 2 weeks, due to the large number of samples to be tested. 

The usual method for obtaining samples at significant depths below the surface is to push or drive a pipe or tube into undisturbed soil at the bottom of a drill hole. Of course, this process disturbs the soil, particularly when the pipe is heavy walled. Many different kinds and sizes of samplers are used, and the most common is shown in Figure 1.1. This sampler is commonly called a split spoon. When used with the dimensions shown, and hammered into the soil by a free falling, 140 pound weight, dropping 30 inches, this is the Standard Penetration Test (see ASTM Standard D.1586,... 

Hydrogen Cycling, Bonfire, Severe Drop Impact Test, Flaw Tolerance, Acid Environment, Gunfire Penetration,... 

Water penetration rates are usually calculated according to the gas laws from measurement of pressure decay upstream of the filler over the whole period of testing with the gas (air) volume above the fluid held constant. They are therefore subject to temperature variations. Although the principle of the water penetration test is sound, and the avoidance of the use of potentially adulterating solvents is attractive, the low rates of water penetration calculable from only very small pressure drops within test systems have raised doubts about the robustness of the method for routine application in its contribution to the decision-making process. 

The authors experimental design included the use of four medium-efficiency fibreglass filter papers of very low variability in order to effectively evaluate filter penetration versus particle diameter. A detailed description of the filters was tabulated and the homogeneity of these samples was demonstrated by the low coefficients of variation shown for both pressure drop and Q127 DOP penetration tests. It was... 

Figure 20.16 shows the typical nail penetration behavior of a Li-Ion cell with shutdown separator. Clearly, there was a voltage drop from 4.2 to 0.0 V, instantaneously, as the nail penetrates through (when internal short circuit occur) and temperature rose. When the heating rate is low, the cell stops heating when the temperature is close to separator shutdown temperature as shown in Fig. 20.16a. If the heating rate is very high, then the cell continues to heat and fails the nail penetration test as shown in Fig. 20.16b. In this case, the separator shutdown is not fast enough to stop the cell from thermal runaway. Thus a separator only helps to avoid delayed failures in case of internal short circnit as simulated by nail and bar crush tests. Separators with high-temperature melt integrity and good shutdown feature (to avoid delayed failures) are needed to pass internal short-circuit tests.

Lenses are tested to withstand the impact of a 2.5-cm (1-inch) ball dropped from 127 cm (50 inches), plus a penetration test for plastic lenses as required by American National Standards Institute (ANSI) Z87 for all eye and face protectors, two-level classification for impact protection. See ANSI Z87.1-2003, Standard for Occupational and Educational Eye and Face Protection Devices. 

Testing in accordance with 49 CFR 173.465, including water spray, free drop, stacking, and penetration tests... 

The Washburn test requires some specialized testing equipment to perform, and an alternate test is the drop penetration time test which is more directly related to the wetting of spray drops into a granulating powder (Hapgood et al., 2003). A drop of known volume is gently placed onto a small powder bed with porosity Sf, and the time taken for the drop to completely sink into the powder bed is measured. The drop penetration time, tp, is given by ... 

The Washburn test and drop penetration time test are closely related, but the latter is simpler to perform as a screening and investigation test when developing or troubleshooting a granulation process. 

The tests are the water spray test, the free drop test, the stacking test and the penetration test. Specimens of the package shall be subjected to the free drop test, the stacking test and the penetration test, preceded in each case by the water spray test. One specimen may be used for all the tests, provided that the requirements of para. 720 are fulfilled. 

One measure of impact resistance is the laminate s mean break height (MBH) (102). In the standard test, there is a 50% probabiHty that a five-pound (2.27-kg) ball will not fall through a laminate if the ball is dropped at the MBH. Typical MBHs for 12 in. (- 30 cm) square laminates prepared with 30 mil (0.76 mm) thick interlayer are 10 ft ( -- 3 m) at 0°F (—18 C) and 15 ft ( -- 4.6 m) at 70°F (2I°C). Figure 2 shows a relationship between adhesion and falling ball penetration resistance measured at 2I°C. 

Alcohol holdout tests, which are also used to measure aqueous fluid repeUency, iavolve placing drops of aqueous isopropyl alcohol solutions of concentrations 10, 20,. .. 100 wt % on a fabric surface. The rating for the fabric is based on the most concentrated solution that does not penetrate the fabric ia the specified time frame (3M Water RepeUency Test II, Water/Alcohol Drop Test (41) INDA Standard Test 80.6). 

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